ECU and Wideband O2 ready to rock and roll…

For the last few months I’ve been planning and working towards turbo-charging my daily driver, a 1996 Toyota RAV4.  Great car, but a bit slow and gutless, hence the upgrade.

Step one is to get a tunable ECU in and running.  I have gone for a DIYAutotune Microsquirt DIYPNP module, which is actually a great little unit.  Now that I’m getting close to having the ECU in and running, I need to be able to tune it, which requires monitoring the Air/Fuel ratios using a wideband O2 sensor.  My car, as standard, only has a narrowband which just isn’t good enough.  So here’s how to fit an Innovative LC-1 wideband O2 sensor to a 1996 Toyota RAV4.

The new sensor has all been calibrated and tested and working fine.  For now, I’m running one of the outputs in narrowband mode back to the stock ECU.  The second output is in wideband mode and wired up to an unused pin on the 12pin connector for the ECU.  To get the Microsquirt to use that I now just have to re-wire the O2 input to that pin.  Should be a snap.

This is the stock O2 sensor on the exhaust manifold with the heat shield removed.

If you’re pulling out a stock O2 sensor, the trick is to do it while the exhaust is hot.  I now this sounds counter intuitive because you’ll probably burn yourself, it’s a must.  While the exhaust is hot, the metal is expanded and it should be easier to loosen the sensor.  While it’s cold this will be almost impossible without breaking the sensor.  Make sure you protect yourself though.  If you have high-temp gloves, use them.  I didn’t so I just wrapped an old t-shirt around my hand and was extra careful.

Once it’s out, should look like this:

At this point I test fitted the wideband sensor which fortunately fit into the stock bung.  This would have been a deal breaker and I’d be stuck tuning with the narrowband.  This is also why you should be careful pulling out the stock sensor because you never know when you’ll need it again, so breaking it is not cool.

Don’t actually fit the O2 sensor as it needs to stay out for calibration.

Next I mounted the Innovative LC-1 module.  I decided to strap it to the main wiring harness as the cable from the sensor was the perfect length to reach there.  To do this, you should probably pull the battery and battery base panel out.  That just makes it easier to get to.

Here’s the module strapped to the harness

Here it is from the engine side so you can see how tucked away and safe it is:

Next, feed the LC-1 main lead and serial leads through the firewall grommet and into the cabin.

 

Now, on to wiring up the LC-1 module to the ECU wiring harness.  First, you need to hook up the LED and push button.  These are required for normal operation, but you’d be stupid not to add them in now while you’re at it as they are useful for calibrating and checking status.

Next, ground the system.  This is always the first thing I do and is a good rule of thumb.  If you ground things properly first, then there’s less chance of voltage trying to find another path of least resistance, like your body.  While 12v won’t do anything to a person, this is a rule I live by across the board.

I used the two grounds on pins 13 & 26 of E4 on the ECU connector.  One is slightly thicker, so I used that for the heater ground.

Next I bridged the LC-1 output #1, which is set to narrowband mode by default, to the stock ECU O2 sensor input.

Lastly is a bit of power.  I just bridged the ECU switched 12v.  The current draw shouldn’t be enough to blow the 15A fuse on that line.

Once that’s all hooked up you can turn it on WITHOUT the sensor connected to the LC-1 module.  This forces calibration next time it’s connected.  Let the LED flash for 30 seconds.  Then turn it off, hook up the sensor and turn it back on.  The LED should flash slowly while the sensor warms up, then it will flash faster during heater calibration.  Once the LED lights steady, hold the button for 30 seconds during which the LED will be off.  Release the button and the LED will flick on for a sec, then go off while it’s calibrating.  When it’s all done the LED will light up steady and you’re good to go.

After this I hooked up the serial port and tested the AFRs on the stock ECU.  Currently running about 13.8 at idle which is about right.  Sweet!